<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>结构性元素2</title>
        <style>
            body{
                background-color: #aaa;
            }
            header{
                width:100%;
                margin:0 auto;
                text-align: center;
                background-color: #fff;
                height:60px;
                margin-bottom: 5px;
                border:1px solid #000;
            }
            nav{
                width:100%;
                margin:0 auto;
                text-align: center;
                background-color: #fff;
                height:30px;
                margin-bottom: 5px;
                border:1px solid #000;
            }
            section{
                width:100%;
                margin:0 auto;
                background-color: #eee;
                margin-bottom:10px;
                text-align: center; 
                border:1px solid #000;
            }
            article{
                width:60%;
                height:500px;
                display:inline-block;
                vertical-align: top;
                background-color: #fff;
                border:1px solid #000;
            }
            aside{
                width:35%;
                height:500px;
                display:inline-block;
                vertical-align: top;
                background-color: #fff;
                border:1px solid #000;
            }
            footer{
                width:100%;
                margin:0 auto;
                text-align: center; 
                background-color: #fff;
                height:30px;
                margin-bottom: 5px;
                border:1px solid #000;
            }
        </style>
    </head>
    <body>
        <header>
            &lt;header&gt;
        </header>
        <nav>
            &lt;nav&gt;
        </nav>
        <section>
            &lt;section&gt;
            <br>
            <article>
                &lt;article&gt;
            </article>
            <aside>
                &lt;aside&gt;
            </aside>
        </section>
        <footer>
            &lt;footer&gt;
        </footer>
    </body>
</html>